SECTIONAL TRANSACTIONS. 



(For reference to tlie publication elsewhere of communications entered in the following 

 lists of transactions, see end of volume, preceding index.) 



SECTION A. 

 MATHEMATICAL AND PHYSICAL SCIENCES. 



Thursday, September 4. 



Discussion on The Meteorological Relations of Atmospherics. (Mr. R. A. 

 Watson Watt ; Prof. E. V. Appleton, F.R.S. ; Monsieur R. 

 Bureau ; Mr. M. A. Giblett.) 



Mr. R. A. Watson Watt.- — -The immediately active work on the origin of 

 atmospherics appears to be associable with the names of Appleton, Austin, Bureau, 

 Dean and Harper, Lugeon, Paolini, Schindelhauer and Watson Watt. The author's 

 conception of the present working hypothesis of each worker is stated in order to 

 de-limit the scope of the present discussion. The experimental methods of each group 

 are summarised and criticised. The examination is illustrated by discussion of 

 typical cases. An attempt is made to state the most definite conclusions as to the 

 meteorological relations of atmospherics which a normally critical physicist would 

 regard as justified by the existing experimental evidence. Suggestions are made for 

 critical tests to resolve some of the differences of view. 



M. R. BuEEAtr. — ' The recording of the Number of Atmospherics per minute.' 



1. The principle of the method of recording atmospherics. 



2. The different processes employed to arrest the transmissions in order to allow 

 the atmospherics only to pass. 



3. Choice of scale for the recorder. Detailed and condensed curves. Rapid 

 publication of curves. 



4. Recording of different categories of atmospherics. Separation of feeble 

 atmospherics from strong atmospherics. 



5. Registration on different wave-lengths. Simultaneity and non-simultaneity 

 of individual atmospherics on different wave-lengths. Influence of wave-lengths on 

 diurnal variation. The part played by propagation in these phenomena. 



6. Comparison of results obtained at Mt. Valerien and St. Cyr. 



7. Examples of long range and of local atmospherics. 



8. The amplitude of the night maximum. Variations in the same latitude and 

 along the same meridian. 



Prof. E. V. Appleton, F.R.S. — In a discussion with this title it seems desirable 

 to ascertain whether a case for a predominantly terrestrial origin for atmospherics 

 can be made out. The various extra-terrestrial sources which have been suggested 

 are, therefore, considered. The thunderstorm mechanism seems to be a more likely 

 source than the extra-terrestrial sources proposed. 



Attention is called to the experimental fact found by Appleton, Watt and Herd 

 that, for atmospherics of local origin, negative electrostatic field changes are about 

 1'6 times as frequent as positive, while for those of distant origin positive radiation 

 field changes are about l-S times as frequent as negative. The possible significance 

 of this is briefly discussed. 



Mr. M. A. Giblett. — Observations of the sources of atmospherics made at the 

 Radio Research Station, Slough, Bucks, at 13-00 G.M.T. daily have been transmitted 

 immediately in an experimental code to the Meteorological Office, Royal Airship 

 Works, Cardington, Beds, where they have been plotted on and studied in connection 

 with the current synoptic weather charts. The results of this experiment in including 

 such observations in a daily weather service will be outlined. 



Prof. M. SiEGBAHN. — The Highly Ionised Spectra in the Extreme Ultra- 

 violet. 



